Lapping machines, such as lapping machine 10 shown in FIG. 1, typically include at least a ring sprocket 16 having a lower lapping wheel 128 and a center sprocket 12. The ring sprocket 16 has a radius 18 and center sprocket 12 has a radius 14. During operation of lapping machine 10, center sprocket 12 rotates about a center axis 24. Teeth of a carrier 20 mesh with the teeth of ring sprocket 16 and the teeth of center sprocket 12 so that carrier 20 is urged into simultaneous rotational movement about its center axis 26 and planetary movement between radius 14 and radius 18. Carrier 20 includes one or more openings 22 for carrying a work piece 28, such as a disk that is exposed to lower lapping wheel 128 during operation. The diameter 30 of carrier 20 is a fixed distance, equal to the difference between radius 18 of ring sprocket 16 and radius 14 of center sprocket 12. As a result, if a carrier 20 having a diameter greater than diameter 30 is desired, it would be necessary to replace at least one of the center sprocket 12 and ring sprocket 16, which is a costly proposition. In addition, with the construction of lapping machine 10, it is similarly apparent that the maximum size of a disk work piece 28 must be less than diameter 30.
Such known machines suffer from the drawback that to accommodate a larger size carrier, the machine must be significantly enlarged, taking up a similarly increased amount of space in a manufacturing facility, thereby reducing production efficiencies. In addition, storage provisions must be made to store differently sized lapping wheel not in use. Further, in the event larger carriers, even only incrementally larger carriers, can be used for applications previously unknown, these machines lack the flexibility to accommodate the marginally larger carrier, unless further sizable investment in a larger lapping wheel is made.
What is needed is a lapping machine that can accommodate differently sized carriers, and further, can accommodate carriers, and even work pieces, having a dimension greater than the difference between the radius of the ring sprocket and the radius of the center sprocket.